Many circumstances arise in day-to-day manufacturing or processing applications that generate an excess in fluid pressure. If not relieved, such pressure can detrimentally affect operation, lead to machine malfunction, etc. Accordingly, various systems have been employed to vent excess pressure to atmosphere. Such systems can be as straightforward as an exhaust pipe or other fixed bleed orifice which constantly exhausts pressure to atmosphere. However, such devices are inherently inefficient due to constant release or loss of pressure.
In still further devices, such as general pressure relief valves, excess pressure is released to atmosphere only when internal pressure reaches a set point. At the set point, the relief valve “trips”, thereby opening an orifice to atmosphere to relieve pressure. Such devices can thus be characterized as working in a bi-stable mode with a single set point. The device cannot therefore be adjusted or efficiently tailored to a dynamic environment once installed. U.S. Pat. No. 3,026,800 provides one example of such a device.
A need therefore exists to keep machines from ever reaching an extreme level of internal pressure. Diffusers are implemented in various machines to provide an outlet for such relief of excess internal pressure. Furthermore, such machines generally operate under a variety of extreme conditions, such as within petroleum and chemical processing facilities, power generator plants, boilers and the like. Given the extreme pressure and temperature ranges under which such machines operate the diffuser must be designed such that it does not adversely alter plant operations.
Conventional vent applications generally require a large control valve, actuator, and noise attenuating trim acting in concert with a fixed diffuser. In general, the control valve receives a signal indicative of fluid pressure and operates the actuator to relieve pressure when necessary. However, a problem with such a system is that conventional diffusers are unable to optimally perform outside a narrow range of operating conditions due to their fixed structure design. More specifically, the fixed state of the diffuser makes optimization difficult, in that the size of the diffuser cannot be altered when the level of internal pressure or fluid flow rate changes. Moreover, the large control valve and actuator burden those in the art with the necessity of adding such cumbersome and expensive components to the vent applications.
An existing option for the relief of undesired pressure is the use of a throttling vent valve. Conventional throttling vent valves utilize a pneumatic actuator directly connected to a throttling plug located inside the diffuser device. This requires the use of large actuators and can limit the application because of temperature concerns due to the close proximity of the actuators to the vent applications that generate and utilize pressure.
It can therefore be seen that there still remains a need for a diffuser that can operate optimally, even at the extreme conditions under which pressure generating or utilizing vent applications operate, while doing so in a reliable, compact, and inexpensive manner.